A lithium secondary battery, which is charged and discharged through oxidation/reduction of lithium ions, includes a cathode, an anode, an ion exchange membrane between the cathode and the anode, and an electrolyte.
For systems that require large-capacity batteries, such as electric vehicles, there is a need to increase capacity of an anode active material used in such a lithium secondary battery and increase output characteristics and lifetime characteristics of the lithium secondary battery. To this end, there is a need for development of a stable alloy-based anode material having a high capacity, instead of conventional carbonaceous anode materials.
A conventional carbonaceous anode active material has merely a theoretical capacity of about 372 mAh/g, and significantly reduced output characteristics, particularly in a high-rate charging condition, due to a mechanism of intercalation and deintercalation of lithium ions in a carbon interlayer during charging and discharging.
An alloy-based material that is currently under research also has fairly low electrical conductivity and may undergo considerable volume expansions during charging and discharging, leading to severe damage of electrode plates and a sharp reduction in capacity. Therefore, there are difficulties in commercializing the alloy-based material.